Form css pseudo class

CSS Pseudo-classes: Forms

Yesterday we started looking at pseudo-classes that relate to links. In this article, we’ll take a look at form-related pseudo-classes.

I’ve split this up into a series of four, where this is the second part about form pseudo-states.

Form pseudo-states permalink

Another significant use case for pseudo-classes is forms. We already had a glimpse at the focus states, which can also be used on form elements.

• :disabled : Element is disabled
• :enabled : Element is active. However, is the default case so rarely used
• :checked : Checkbox/radio is checked
• :indeterminate : Checkbox/radio is not true or false
• :placeholder-shown : Placeholder is active and has no value
• :valid : Field is valid
• :invalid : Field is invalid
• :in-range : Number field is in a range of options
• :required : Field is required
• :optional : Field is optional, again a default state so rarely used

:disabled & :enabled permalink

As mentioned in the descriptive text for :enabled , it’s also a default state, so it’s not often used. As we instead use the main selector to style on.

We can use the :disabled state to indicate when a form field is disabled, and the user can’t change anything.

Let’s say we have a button that is disabled until they fill out all fields, for instance. It’s an excellent way to showcase that it’s not yet valid to the user.

button:disabled  background: lightGray; color: #333; cursor: not-allowed; >

You can see the difference in the following CodePen.

:checked & :indeterminate permalink

The checked and indeterminate pseudo-classes can help style checkboxes and radio buttons.

The checked class will fire if the element is on, and indeterminate is funny as it targets non-binary states.

What does that even mean? A checkbox can be on/off right, but there are rare cases where it can be neither. And that’s precisely where indeterminate kicks in.

Note: To be honest never needed it in my life

How can we style with the checked state?

input[type='checkbox']:checked  box-shadow: 0 0 0 3px hotpink; >

I’m using the box-shadow here as this is one view that works well for checked states.

If you plan to style the checkbox further, it might be best to opt for a custom checkbox.

As for the indeterminate , it’s not worth going into detail here as it’s such a niche use case.

CSS-tricks has an excellent article on it if you wish more information.

Try it out in this CodePen.

:placeholder-shown permalink

Before, I dedicated a more detailed article about the CSS :placeholder-shown pseudo class.

It can be used to indicate which fields have their placeholder showing.

input:placeholder-shown  border: 5px dashed teal; >

See the Pen `:checked` by Chris Bongers (@rebelchris) on CodePen.

Note: Try and add a value in the bottom input. It should change the appearance.

:valid , :invalid , & :in-range permalink

These are validation classes and can be used to showcase a un valid field.

Let’s use an email field. It’s the easiest to showcase both the invalid and the valid states.

We can add a red/green border and shadow based on the validation state like so:

input:invalid  border: 2px solid red; box-shadow: 0 0 2px red; outline: red; > input:valid  border: 2px solid green; box-shadow: 0 0 2px green; outline: green; >

You can try it out in the below CodePen by adding a non-email and email value.

The in-range one is in line with these two and can be used for number fields to determine if they are in the correct range.

input:in-range  border: 2px solid green; box-shadow: 0 0 2px green; outline: green; >

You can also try this one out, but pick a number between 1 and 10. (Which is the range for the number input)

:required & :optional permalink

This can be used to determine if a field is required or not. The optional state is the default state, so it is unnecessary to state this explicitly.

input:required  background: orange; >

This will give all required fields an orange background.

Thank you for reading, and let’s connect! permalink

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Pseudo-classes

A CSS pseudo-class is a keyword added to a selector that specifies a special state of the selected element(s). For example, the pseudo-class :hover can be used to select a button when a user’s pointer hovers over the button and this selected button can then be styled.

/* Any button over which the user's pointer is hovering */ button:hover  color: blue; > 

A pseudo-class consists of a colon ( : ) followed by the pseudo-class name (e.g., :hover ). A functional pseudo-class also contains a pair of parentheses to define the arguments (e.g., :dir() ). The element that a pseudo-class is attached to is defined as an anchor element (e.g., button in case button:hover ).

Pseudo-classes let you apply a style to an element not only in relation to the content of the document tree, but also in relation to external factors like the history of the navigator ( :visited , for example), the status of its content (like :checked on certain form elements), or the position of the mouse (like :hover , which lets you know if the mouse is over an element or not).

Note: In contrast to pseudo-classes, pseudo-elements can be used to style a specific part of an element.

Element display state pseudo-classes

These pseudo-classes enable the selection of elements based on their display states.

Matches an element that is currently in fullscreen mode.

Matches an element that is in a state in which it excludes all interaction with elements outside it until the interaction has been dismissed.

Matches an element that is currently in picture-in-picture mode.

Input pseudo-classes

These pseudo-classes relate to form elements, and enable selecting elements based on HTML attributes and the state that the field is in before and after interaction.

Represents a user interface element that is in an enabled state.

Represents a user interface element that is in a disabled state.

Represents any element that cannot be changed by the user.

Represents any element that is user-editable.

Matches an input element that is displaying placeholder text. For example, it will match the placeholder attribute in the and elements.

Matches one or more UI elements that are the default among a set of elements.

Matches when elements such as checkboxes and radio buttons are toggled on.

Matches UI elements when they are in an indeterminate state.

Matches a user-input element which is empty, containing an empty string or other null input.

Matches an element with valid contents. For example, an input element with the type ’email’ that contains a validly formed email address or an empty value if the control is not required.

Matches an element with invalid contents. For example, an input element with type ’email’ with a name entered.

Applies to elements with range limitations. For example, a slider control when the selected value is in the allowed range.

Applies to elements with range limitations. For example, a slider control when the selected value is outside the allowed range.

Matches when a form element is required.

Matches when a form element is optional.

Represents an element with incorrect input, but only when the user has interacted with it.

Linguistic pseudo-classes

These pseudo-classes reflect the document language and enable the selection of elements based on language or script direction.

The directionality pseudo-class selects an element based on its directionality as determined by the document language.

Select an element based on its content language.

Location pseudo-classes

These pseudo-classes relate to links, and to targeted elements within the current document.

Matches an element if the element would match either :link or :visited .

Matches links that have not yet been visited.

Matches links that have been visited.

Matches links whose absolute URL is the same as the target URL. For example, anchor links to the same page.

Matches the element which is the target of the document URL.

Matches elements which are the target of the document URL, but also elements which have a descendant which is the target of the document URL.

Represents elements that are a reference point for selectors to match against.

Resource state pseudo-classes

These pseudo-classes apply to media that is capable of being in a state where it would be described as playing, such as a video.

Represents a media element that is capable of playing when that element is playing.

Represents a media element that is capable of playing when that element is paused.

Time-dimensional pseudo-classes

These pseudo-classes apply when viewing something which has timing, such as a WebVTT caption track.

Represents the element or ancestor of the element that is being displayed.

Represents an element that occurs entirely before the :current element.

Represents an element that occurs entirely after the :current element.

Tree-structural pseudo-classes

These pseudo-classes relate to the location of an element within the document tree.

Represents an element that is the root of the document. In HTML this is usually the element.

Represents an element with no children other than white-space characters.

Uses An+B notation to select elements from a list of sibling elements.

Uses An+B notation to select elements from a list of sibling elements, counting backwards from the end of the list.

Matches an element that is the first of its siblings.

Matches an element that is the last of its siblings.

Matches an element that has no siblings. For example, a list item with no other list items in that list.

Uses An+B notation to select elements from a list of sibling elements that match a certain type from a list of sibling elements.

Uses An+B notation to select elements from a list of sibling elements that match a certain type from a list of sibling elements counting backwards from the end of the list.

Matches an element that is the first of its siblings, and also matches a certain type selector.

Matches an element that is the last of its siblings, and also matches a certain type selector.

Matches an element that has no siblings of the chosen type selector.

User action pseudo-classes

These pseudo-classes require some interaction by the user in order for them to apply, such as holding a mouse pointer over an element.

Matches when a user designates an item with a pointing device, such as holding the mouse pointer over the item.

Matches when an item is being activated by the user. For example, when the item is clicked on.

Matches when an element has focus.

Matches when an element has focus and the user agent identifies that the element should be visibly focused.

Matches an element to which :focus applies, plus any element that has a descendant to which :focus applies.

Functional pseudo-classes

These pseudo-classes accept a selector list or forgiving selector list as a parameter.

The matches-any pseudo-class matches any element that matches any of the selectors in the list provided. The list is forgiving.

The negation, or matches-none, pseudo-class represents any element that is not represented by its argument.

The specificity-adjustment pseudo-class matches any element that matches any of the selectors in the list provided without adding any specificity weight. The list is forgiving.

The relational pseudo-class represents an element if any of the relative selectors match when anchored against the attached element.

Syntax

selector:pseudo-class  property: value; > 

Like regular classes, you can chain together as many pseudo-classes as you want in a selector.

Alphabetical index

Pseudo-classes defined by a set of CSS specifications include the following:

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